Methods and apparatuses for determining a type of control field

ABSTRACT

Systems, method and apparatus of managing wireless communication are described herein.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application No.61/387,542, filed Sep. 29, 2010; U.S. Provisional Application No.61/389,495, filed Oct. 4, 2010; U.S. Provisional Application No.61/405,283, filed Oct. 21, 2010; U.S. Provisional Application No.61/422,098, filed Dec. 10, 2010; U.S. Provisional Application No.61/432,115, filed Jan. 12, 2011; U.S. Provisional Application No.61/405,194, filed Oct. 20, 2010; and U.S. Provisional Application No.61/409,645, filed Nov. 3, 2010; the entire content of each of which isincorporated herein by reference. This application further claims thebenefit of U.S. Provisional Application No. 61/414,651, filed Nov. 17,2010. This application is related to U.S. application Ser. No.13/247,023, titled “SYSTEMS AND METHODS FOR COMMUNICATION OF CHANNELSTATE INFORMATION,” filed on even date herewith, U.S. application Ser.No. 13/247,047 titled “SYSTEMS AND METHODS FOR COMMUNICATION OF CHANNELSTATE INFORMATION,” filed on even date herewith, U.S. application Ser.No. 13/247,062, titled “SYSTEMS AND METHODS FOR COMMUNICATION OF CHANNELSTATE INFORMATION,” filed on even date herewith, U.S. application Ser.No. 13/247,086, titled “SYSTEMS AND METHODS FOR COMMUNICATION OF CHANNELSTATE INFORMATION,” filed on even date herewith, U.S. application Ser.No. 13/247,100, titled “SYSTEMS, METHODS AND APPARATUS FOR DETERMININGCONTROL FIELD AND MODULATION CODING SCHEME INFORMATION,” filed on evendate herewith, U.S. application Ser. No. 13/247,144, titled “SYSTEMS,METHODS AND APPARATUS FOR DETERMINING CONTROL FIELD AND MODULATIONCODING SCHEME INFORMATION,” filed on even date herewith, each of whichare incorporated herein by reference, in their entirety.

BACKGROUND

Field

The present disclosure generally relates to wireless communications.

Background

In order to address the issue of increasing bandwidth requirementsdemanded for wireless communications systems, different schemes arebeing developed to allow multiple user terminals to communicate with asingle access point by sharing the channel resources while achievinghigh data throughputs. Multiple Input Multiple Output (MIMO) technologyrepresents one such approach that has recently emerged as a populartechnique for next generation communication systems. MIMO technology hasbeen adopted in several emerging wireless communications standards suchas the Institute of Electrical and Electronics Engineers (IEEE) 802.11standard. The IEEE 802.11 denotes a set of Wireless Local Area Network(WLAN) air interface standards developed by the IEEE 802.11 committeefor short-range communications (e.g., tens of meters to a few hundredmeters).

A MIMO system employs multiple (N_(T)) transmit antennas and multiple(N_(R)) receive antennas for data transmission. A MIMO channel formed bythe N_(T) transmit and N_(R) receive antennas may be decomposed intoN_(S) independent channels, which are also referred to as spatialchannels, where N_(S)≦min{N_(T), N_(R)}. Each of the N_(S) independentchannels corresponds to a dimension. The MIMO system can provideimproved performance (e.g., higher throughput and/or greaterreliability) if the additional dimensionalities created by the multipletransmit and receive antennas are utilized.

In wireless networks with a single Access Point (AP) and multiple userstations (STAs), concurrent transmissions may occur on multiple channelstoward different stations, both in the uplink and downlink direction.Many challenges are present in such systems.

SUMMARY

Various aspects of systems, methods and devices within the scope of theappended claims each have several aspects, no single one of which issolely responsible for the desirable attributes described herein.Without limiting the scope of the appended claims, some prominentfeatures are described herein. After considering this discussion, andparticularly after reading the section entitled “Detailed Description”one will understand how the features of various aspects are used tomanage monitoring of a page channel or the like.

Certain aspects of this disclosure provide a method of wirelesscommunication. The method comprises receiving a first frame having acontrol field. The method comprises determining whether the controlfield comprises a first type or a second type based at least in part onthe control field. The method comprises processing the control fieldbased on the determined type.

Certain aspects of this disclosure provide an apparatus for wirelesscommunication. The apparatus comprises a receiver configured to receivea first frame having a control field. The apparatus comprises aprocessing system. The processing system is configured to determinewhether the control field comprises a first type or a second type basedat least in part on the control field. The processing system isconfigured to process the control field based on the determined type.

Certain aspects of this disclosure provide an apparatus for wirelesscommunication. The apparatus comprises means for receiving a first framehaving a control field. The apparatus comprises means for determiningwhether the control field comprises a first type or a second type basedat least in part on the control field. The apparatus comprises means forprocessing the control field based on the determined type.

Certain aspects of this disclosure provide a computer program productfor wirelessly communicating comprising a computer readable medium. Thecomputer readable medium comprises instructions. The instructions whenexecuted cause an apparatus to receive a first frame having a controlfield. The instructions when executed cause an apparatus to determinewhether the control field comprises a first type or a second type basedat least in part on the control field. The instructions when executedcause an apparatus to process the control field based on the determinedtype.

Certain aspects of this disclosure provide user terminal for wirelesscommunication. The user terminal comprises an antenna. The user terminalcomprises a receiver configured to receive, via the antenna, a framehaving a control field. The user terminal comprises a processing system.The processing system is configured to determine whether the controlfield comprises a first type or a second type based at least in part onthe control field. The processing system is configured to process thecontrol field based on the determined type.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which features of the present disclosure can beunderstood in detail, a more particular description, briefly summarizedabove, may be had by reference to aspects, some of which are illustratedin the appended drawings. It is to be noted, however, that the appendeddrawings illustrate only certain typical aspects of this disclosure andare therefore not to be considered limiting of its scope, for thedescription may admit to other equally effective aspects.

FIG. 1 is a diagram of a wireless communications network in accordancewith certain aspects of the present disclosure.

FIG. 2 is a block diagram of an example access point and user terminalsin accordance with certain aspects of the present disclosure.

FIG. 3 is a block diagram of an example wireless device in accordancewith certain aspects of the present disclosure.

FIG. 4A is a schematic diagram of a data unit in accordance with certainaspects of the present disclosure.

FIG. 4B illustrates an example of a frame that includes the header ofthe data unit of FIG. 4A.

FIG. 4C illustrates an example of a frame control field of the header ofthe data unit of FIG. 4A.

FIG. 4D illustrates an example of a control field of the header of thedata unit of FIG. 4A.

FIG. 5A is a flowchart of an implementation of a method.

FIG. 5B is a flowchart of an implementation of a method.

FIG. 6A is a flowchart of an implementation of a method.

FIG. 6B is a flowchart of an implementation of a method.

FIG. 7A is a flowchart of an implementation of a method.

FIG. 7B illustrates an example of a link adaptation control subfieldhaving an indicator that is at least four bits.

FIG. 8 is a flowchart of an implementation of a method.

FIG. 9A is a flowchart of an implementation of a method.

FIG. 9B is a flowchart of an implementation of a method.

FIG. 10 illustrates an exemplary channel state information (CSI)feedback protocol.

FIG. 11 illustrates an exemplary Null Data Packet Announcement (NDPA)frame.

FIG. 12 illustrates a block diagram of an example user terminal inaccordance with certain aspects of the present disclosure.

In accordance with common practice the various features illustrated inthe drawings may not be drawn to scale. Accordingly, the dimensions ofthe various features may be arbitrarily expanded or reduced for clarity.In addition, some of the drawings may not depict all of the componentsof a given system, method or device. Finally, like reference numeralsmay be used to denote like features throughout the specification andfigures.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein one skilled in the art should appreciate that the scopeof the disclosure is intended to cover any aspect of the disclosuredisclosed herein, whether implemented independently of or combined withany other aspect of the disclosure. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition toor other than the various aspects of the disclosure set forth herein. Itshould be understood that any aspect of the disclosure disclosed hereinmay be embodied by one or more elements of a claim.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

The techniques described herein may be used for various broadbandwireless communication systems, including communication systems that arebased on an orthogonal multiplexing scheme. Examples of suchcommunication systems include Spatial Division Multiple Access (SDMA),Time Division Multiple Access (TDMA), Orthogonal Frequency DivisionMultiple Access (OFDMA) systems, Single-Carrier Frequency DivisionMultiple Access (SC-FDMA) systems, and so forth. An SDMA system mayutilize sufficiently different directions to simultaneously transmitdata belonging to multiple user terminals. A TDMA system may allowmultiple user terminals to share the same frequency channel by dividingthe transmission signal into different time slots, each time slot beingassigned to different user terminal. A TDMA system may implement GSM orsome other standards known in the art. An OFDMA system utilizesorthogonal frequency division multiplexing (OFDM), which is a modulationtechnique that partitions the overall system bandwidth into multipleorthogonal sub-carriers. These sub-carriers may also be called tones,bins, etc. With OFDM, each sub-carrier may be independently modulatedwith data. An OFDM system may implement IEEE 802.11 or some otherstandards known in the art. An SC-FDMA system may utilize interleavedFDMA (IFDMA) to transmit on sub-carriers that are distributed across thesystem bandwidth, localized FDMA (LFDMA) to transmit on a block ofadjacent sub-carriers, or enhanced FDMA (EFDMA) to transmit on multipleblocks of adjacent sub-carriers. In general, modulation symbols are sentin the frequency domain with OFDM and in the time domain with SC-FDMA. ASC-FDMA system may implement 3GPP-LTE (3^(rd) Generation PartnershipProject Long Term Evolution) or some other standards known in the art.

The teachings herein may be incorporated into (e.g., implemented withinor performed by) a variety of wired or wireless apparatuses (e.g.,nodes). In some aspects, a wireless node implemented in accordance withthe teachings herein may comprise an access point or an access terminal.

An access point (“AP”) may comprise, be implemented as, or known asNodeB, Radio Network Controller (“RNC”), eNodeB, Base Station Controller(“BSC”), Base Transceiver Station (“BTS”), Base Station (“BS”),Transceiver Function (“TF”), Radio Router, Radio Transceiver, BasicService Set (“BSS”), Extended Service Set (“ESS”), Radio Base Station(“RBS”), or some other terminology

An access terminal (“AT”) may comprise, be implemented as, or known asan access terminal, a subscriber station, a subscriber unit, a mobilestation, a remote station, a remote terminal, a user terminal, a useragent, a user device, user equipment, a user station, or some otherterminology. In some implementations an access terminal may comprise acellular telephone, a cordless telephone, a Session Initiation Protocol(“SIP”) phone, a wireless local loop (“WLL”) station, a personal digitalassistant (“PDA”), a handheld device having wireless connectioncapability, a Station (“STA”), or some other suitable processing deviceconnected to a wireless modem. Accordingly, one or more aspects taughtherein may be incorporated into a phone (e.g., a cellular phone or smartphone), a computer (e.g., a laptop), a portable communication device, aportable computing device (e.g., a personal data assistant), anentertainment device (e.g., a music or video device, or a satelliteradio), a global positioning system device, or any other suitable devicethat is configured to communicate via a wireless or wired medium. Insome aspects the node is a wireless node. Such wireless node mayprovide, for example, connectivity for or to a network (e.g., a widearea network such as the Internet or a cellular network) via a wired orwireless communication link.

In some aspects the teachings herein may be employed in a network thatincludes macro scale coverage (e.g., a large area cellular network suchas a 3G network, typically referred to as a macro cell network) andsmaller scale coverage (e.g., a residence-based or building-basednetwork environment). As an AT or UE moves through such a network, theaccess terminal may be served in certain locations by ANs that providemacro coverage while the access terminal may be served at otherlocations by access nodes that provide smaller scale coverage. In someaspects, the smaller coverage nodes may be used to provide incrementalcapacity growth, in-building coverage, and different services (e.g., fora more robust user experience). In the discussion herein, a node thatprovides coverage over a relatively large area may be referred to as amacro node. A node that provides coverage over a relatively small area(e.g., a residence) may be referred to as a femto node. A node thatprovides coverage over an area that is smaller than a macro area andlarger than a femto area may be referred to as a pico node (e.g.,providing coverage within a commercial building).

A cell associated with a macro node, a femto node, or a pico node may bereferred to as a macro cell, a femto cell, or a pico cell, respectively.In some implementations, each cell may be further associated with (e.g.,divided into) one or more sectors.

In various applications, other terminology may be used to reference amacro node, a femto node, or a pico node. For example, a macro node maybe configured or referred to as an access node, base station, accesspoint, eNodeB, macro cell, and so on. Also, a femto node may beconfigured or referred to as a Home NodeB (HNB), Home eNodeB (HeNB),access point base station, femto cell, and so on.

FIG. 1 illustrates a multiple-access multiple-input multiple-output(MIMO) system 100 with access points and user terminals. For simplicity,only one access point 110 is shown in FIG. 1. An access point isgenerally a fixed station that communicates with the user terminals andmay also be referred to as a base station or some other terminology. Auser terminal may be fixed or mobile and may also be referred to as amobile station, a wireless device or some other terminology. Accesspoint 110 may communicate with one or more user terminals 120 at anygiven moment on the downlink and uplink. The downlink (i.e., forwardlink) is the communication link from the access point to the userterminals, and the uplink (i.e., reverse link) is the communication linkfrom the user terminals to the access point. A user terminal may alsocommunicate peer-to-peer with another user terminal. A system controller130 couples to and provides coordination and control for the accesspoints.

While portions of the following disclosure will describe user terminals120 capable of communicating via Spatial Division Multiple Access(SDMA), for certain aspects, the user terminals 120 may also includesome user terminals that do not support SDMA. Thus, for such aspects, anAP 110 may be configured to communicate with both SDMA and non-SDMA userterminals. This approach may conveniently allow older versions of userterminals (“legacy” stations) to remain deployed in an enterprise,extending their useful lifetime, while allowing newer SDMA userterminals to be introduced as deemed appropriate.

The system 100 employs multiple transmit and multiple receive antennasfor data transmission on the downlink and uplink. The access point 110is equipped with N_(ap) antennas and represents the multiple-input (MI)for downlink transmissions and the multiple-output (MO) for uplinktransmissions. A set of K selected user terminals 120 collectivelyrepresents the multiple-output for downlink transmissions and themultiple-input for uplink transmissions. For pure SDMA, it is desired tohave N_(ap)≧K≧1 if the data symbol streams for the K user terminals arenot multiplexed in code, frequency or time by some means. K may begreater than N_(ap) if the data symbol streams can be multiplexed usingTDMA technique, different code channels with CDMA, disjoint sets ofsub-bands with OFDM, and so on. Each selected user terminal transmitsuser-specific data to and/or receives user-specific data from the accesspoint. In general, each selected user terminal may be equipped with oneor multiple antennas (i.e., N_(ut)≧1). The K selected user terminals canhave the same or different number of antennas.

The SDMA system 100 may be a time division duplex (TDD) system or afrequency division duplex (FDD) system. For a TDD system, the downlinkand uplink share the same frequency band. For an FDD system, thedownlink and uplink use different frequency bands. MIMO system 100 mayalso utilize a single carrier or multiple carriers for transmission.Each user terminal may be equipped with a single antenna (e.g., in orderto keep costs down) or multiple antennas (e.g., where the additionalcost can be supported). The system 100 may also be a TDMA system if theuser terminals 120 share the same frequency channel by dividingtransmission/reception into different time slots, each time slot beingassigned to different user terminal 120.

FIG. 2 illustrates a block diagram of access point 110 and two userterminals 120 m and 120 x in MIMO system 100. The access point 110 isequipped with N_(t) antennas 224 a through 224 t. User terminal 120 m isequipped with N_(ut,m) antennas 252 ma through 252 mu, and user terminal120 x is equipped with N_(ut,x) antennas 252 xa through 252 xu. Theaccess point 110 is a transmitting entity for the downlink and areceiving entity for the uplink. Each user terminal 120 is atransmitting entity for the uplink and a receiving entity for thedownlink. As used herein, a “transmitting entity” is an independentlyoperated apparatus or device capable of transmitting data via a wirelesschannel, and a “receiving entity” is an independently operated apparatusor device capable of receiving data via a wireless channel. In thefollowing description, the subscript “dn” denotes the downlink, thesubscript “up” denotes the uplink, N_(up) user terminals are selectedfor simultaneous transmission on the uplink, N_(dn) user terminals areselected for simultaneous transmission on the downlink, N_(up) may ormay not be equal to N_(dn), and N_(up) and N_(dn) may be static valuesor can change for each scheduling interval. The beam-steering or someother spatial processing technique may be used at the access point anduser terminal.

On the uplink, at each user terminal 120 selected for uplinktransmission, a TX data processor 288 receives traffic data from a datasource 286 and control data from a controller 280. TX data processor 288processes (e.g., encodes, interleaves, and modulates) the traffic datafor the user terminal based on the coding and modulation schemesassociated with the rate selected for the user terminal and provides adata symbol stream. A TX spatial processor 290 performs spatialprocessing on the data symbol stream and provides N_(ut,m) transmitsymbol streams for the N_(ut,m) antennas. Each transmitter unit (TMTR)254 receives and processes (e.g., converts to analog, amplifies,filters, and frequency upconverts) a respective transmit symbol streamto generate an uplink signal. N_(ut,m) transmitter units 254 provideN_(ut,m) uplink signals for transmission from N_(ut,m) antennas 252 tothe access point.

N_(up) user terminals may be scheduled for simultaneous transmission onthe uplink. Each of these user terminals performs spatial processing onits data symbol stream and transmits its set of transmit symbol streamson the uplink to the access point.

At access point 110, N_(ap) antennas 224 a through 224 ap receive theuplink signals from all N_(up) user terminals transmitting on theuplink. Each antenna 224 provides a received signal to a respectivereceiver unit (RCVR) 222. Each receiver unit 222 performs processingcomplementary to that performed by transmitter unit 254 and provides areceived symbol stream. An RX spatial processor 240 performs receiverspatial processing on the N_(ap) received symbol streams from N_(ap)receiver units 222 and provides N_(up) recovered uplink data symbolstreams. The receiver spatial processing is performed in accordance withthe channel correlation matrix inversion (CCMI), minimum mean squareerror (MMSE), soft interference cancellation (SIC), or some othertechnique. Each recovered uplink data symbol stream is an estimate of adata symbol stream transmitted by a respective user terminal. An RX dataprocessor 242 processes (e.g., demodulates, deinterleaves, and decodes)each recovered uplink data symbol stream in accordance with the rateused for that stream to obtain decoded data. The decoded data for eachuser terminal may be provided to a data sink 244 for storage and/or acontroller 230 for further processing.

On the downlink, at access point 110, a TX data processor 210 receivestraffic data from a data source 208 for N_(dn) user terminals scheduledfor downlink transmission, control data from a controller 230, andpossibly other data from a scheduler 234. The various types of data maybe sent on different transport channels. TX data processor 210 processes(e.g., encodes, interleaves, and modulates) the traffic data for eachuser terminal based on the rate selected for that user terminal. TX dataprocessor 210 provides N_(dn) downlink data symbol streams for theN_(dn) user terminals. A TX spatial processor 220 performs spatialprocessing (such as a precoding or beamforming, as described in thepresent disclosure) on the N_(dn) downlink data symbol streams, andprovides N_(ap) transmit symbol streams for the N_(ap) antennas. Eachtransmitter unit 222 receives and processes a respective transmit symbolstream to generate a downlink signal. N_(ap) transmitter units 222providing N_(ap) downlink signals for transmission from N_(ap) antennas224 to the user terminals.

At each user terminal 120, N_(ut,m) antennas 252 receive the N_(ap)downlink signals from access point 110. Each receiver unit 254 processesa received signal from an associated antenna 252 and provides a receivedsymbol stream. An RX spatial processor 260 performs receiver spatialprocessing on N_(ut,m) received symbol streams from N_(ut,m) receiverunits 254 and provides a recovered downlink data symbol stream for theuser terminal. The receiver spatial processing is performed inaccordance with the CCMI, MMSE or some other technique. An RX dataprocessor 270 processes (e.g., demodulates, deinterleaves and decodes)the recovered downlink data symbol stream to obtain decoded data for theuser terminal.

At each user terminal 120, a channel estimator 278 estimates thedownlink channel response and provides downlink channel estimates, whichmay include channel gain estimates, SNR estimates, noise variance and soon. Similarly, a channel estimator 228 estimates the uplink channelresponse and provides uplink channel estimates. Controller 280 for eachuser terminal typically derives the spatial filter matrix for the userterminal based on the downlink channel response matrix H_(dn,m) for thatuser terminal. Controller 230 derives the spatial filter matrix for theaccess point based on the effective uplink channel response matrixH_(up,eff). Controller 280 for each user terminal may send feedbackinformation (e.g., the downlink and/or uplink eigenvectors, eigenvalues,SNR estimates, and so on) to the access point. Controllers 230 and 280also control the operation of various processing units at access point110 and user terminal 120, respectively.

FIG. 3 illustrates various components that may be utilized in a wirelessdevice 302 that may be employed within the wireless communication system100. The wireless device 302 is an example of a device that may beconfigured to implement the various methods described herein. Thewireless device 302 may be a base station 104 or a user terminal 106.

The wireless device 302 may include a processor 304 which controlsoperation of the wireless device 302. The processor 304 may also bereferred to as a central processing unit (CPU). Memory 306, which mayinclude both read-only memory (ROM) and random access memory (RAM),provides instructions and data to the processor 304. A portion of thememory 306 may also include non-volatile random access memory (NVRAM).The processor 304 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 306. Theinstructions in the memory 306 may be executable to implement themethods described herein.

The wireless device 302 may also include a housing 308 that may includea transmitter 310 and a receiver 312 to allow transmission and receptionof data between the wireless device 302 and a remote location. Thetransmitter 310 and receiver 312 may be combined into a transceiver 314.A single or a plurality of transmit antennas 316 may be attached to thehousing 308 and electrically coupled to the transceiver 314. Thewireless device 302 may also include (not shown) multiple transmitters,multiple receivers, and multiple transceivers.

The wireless device 302 may also include a signal detector 318 that maybe used in an effort to detect and quantify the level of signalsreceived by the transceiver 314. The signal detector 318 may detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 302 may alsoinclude a digital signal processor (DSP) 320 for use in processingsignals.

The various components of the wireless device 302 may be coupledtogether by a bus system 322, which may include a power bus, a controlsignal bus, and a status signal bus in addition to a data bus.

The wireless system 100 illustrated in FIG. 1 may operate in accordancewith IEEE 802.11ac wireless communications standard. The IEEE 802.11acrepresents a new IEEE 802.11 amendment that allows for higher throughputin IEEE 802.11 wireless networks. The higher throughput may be realizedthrough several measures such as parallel transmissions to multiplestations (STAs) at once, or by using a wider channel bandwidth (e.g., 80MHz or 160 MHz). The IEEE 802.11ac is also referred to as Very HighThroughput (VHT) wireless communications standard.

FIG. 4A is a schematic diagram of a data unit 400 in accordance withcertain aspects of the present disclosure. In certain aspects, the dataunit 400 may be a physical layer protocol data unit (PPDU), that may betransmitted between devices, such as the access point 110 and userterminals 120, in the wireless communication system 100 of FIG. 1. Thedata unit 400 includes a physical layer (PHY) portion 401 and a mediaaccess control (MAC) header 402. A body portion or MAC frame body (notillustrated) may follow the MAC header 402. Within the MAC header 402,there is a frame control field 403 and an optional control field 404that can be at least one of two types (also referred to as “formats”).For example, in one implementation the control field 404 is a very highthroughput (VHT) control field and in another the control field 404 is ahigh throughput (HT) control field. In some implementations the controlfield 404 is set on a per data unit basis to be one of a VHT controlfield and an HT control field. Further, a device receiving the data unit400 may process the data unit 400 based on which type of control field(e.g., HT or VHT) is included in the MAC header 402. As such, there liesa challenge to determine which type (VHT or HT) of control field ispresent, if one is present at all.

FIG. 4B illustrates an example of a MAC frame 500 that includes the MACheader 402 of FIG. 4A. The MAC frame 500 includes the MAC header 402.The first three fields (the frame control field 403, a duration/ID field504, and an address 1 field 506) and the last field (a frame checksequence (FCS) field 508) constitute the minimal frame format of the MACframe 500, and are present in all MAC frames. The remaining fieldsillustrated below (an address 2 field 511, an address 3 field 512, asequence control field 513, an address 4 field 514, a QoS control field515, the control field 404, and a frame body 522) are present only incertain frame types and subtypes. Although the control field 404 islabeled as an HT control field in the aspect illustrated below, the HTcontrol field 404 may be formatted as HT or as VHT.

FIG. 4C illustrates an example of a frame control field 403 of the MACheader 402 of FIG. 4A. The frame control field 403 includes a protocolversion sub-sub-field comprising 2 bits, a type sub-field comprising 2bits, a subtype sub-field comprising 4 bits, a to ds sub-fieldcomprising 1 bit, a from ds sub-field comprising 1 bit, a more fragsub-field comprising 1 bit, a retry sub-field comprising 1 bit, a powermanagement sub-field comprising 1 bit, a more data sub-field comprising1 bit, a protected frame sub-field comprising 1 bit, and an ordersub-field comprising 1 bit. The last sub-field in the frame controlfield 403 comprises an order field 602 that includes 1 bit. The orderfield 602 may also be referred to as the order bit. When the data unit400 is a HT or VHT data unit, the order bit 602 indicates whether thecontrol field 404 is present in the MAC header 402 (and thus the MACframe 500 and the data unit 400). If the order bit 602 is set to “1,”the control field 404 is present. The control field 404 is not presentif the order bit 602 is set to “0.”

Before a node evaluates the order bit 602 to determine whether thecontrol field 404 is present, the node may first determine whether thedata unit 400 is an HT or VHT data unit. In some aspects, thisdetermination is based on a TXVECTOR in the PHY portion 401 of the dataunit 400.

FIG. 4D illustrates an example of a control field 404 of the MAC header402 of FIG. 4A. The control field includes a VHT field 702 thatindicates whether a sub-field 704 has an HT or VHT format. When the VHTfield 702 is set to “0,” the HT format is used for the sub-field 704.When the VHT field 702 is set to “1,” however, the sub-field 704 has aVHT format. In some aspects, the VHT field 702 comprises a reserved bitin the control field 404. In some aspects, reserved bit comprises thefirst bit in the control field 404. In some aspects, a modulation codingscheme (MCS) feedback (MFB) is indicated in the sub-field 704 inresponse to a solicitation for such feedback as discussed below.

In another aspect, the control field 404 includes at least one of a linkadaptation control subfield that may be 16 bits, a reserved subfieldthat may be 14 bits, an AC constraint subfield that may be 1 bit, and areverse direction grant (RDG) subfield that may be 1 bit. The reservedsubfield may comprise one or more additional subfields.

FIG. 5A is a flowchart of an implementation of a method of determiningwhether a control field is present and its type. As represented by block5A-1, the method includes determining the type of data unit received. Asrepresented by block 5A-2, the method includes determining if the dataunit type is VHT or HT. If the data unit type is HT (HT path from 5A-2),as represented by block 5A-3, the method includes parsing the order bitin the data unit. If the order bit is not set (No path from 5A-3), thereis no control field in the data unit that is either a VHT control fieldor HT control field. On the other hand, if the order bit is set (Yespath from 5A-3), a HT control field is present as represented by block5A-5.

Referring again to block 5B-2, if the data unit type is VHT (VHT pathfrom 5B-2), as represented by block 5B-3, the method includes parsingthe order bit in the data unit. If the order bit is not set (No pathfrom 5A-6), there is no control field in the data unit that is either aVHT control field or HT control field as represented by block 5A-4. Onthe other hand, if the order bit is set (Yes path from 5A-6), a VHTcontrol field is present as represented by block 5A-7.

FIG. 5B is a flowchart of an implementation of another method ofdetermining whether a control field is present and its type. Asrepresented by block 5B-1, the method includes receiving a data unit. Asrepresented by block 5B-2, the method includes parsing the order bit inthe data unit. If the order bit is not set (No path from 5B-2), there isno control field in the data unit that is either a VHT control field orHT control field. On the other hand, if the order bit is set (Yes pathfrom 5B-2), there is a control field in the data unit that is either aVHT control field or HT control field. As represented by block 5B-4, themethod includes parsing the control field for a reserved bit. If thereserved bit is not set (No path from 5B-5), as represented by block5B-6, the method includes deciding that the control field is a HTcontrol field. On the other hand, if the reserved bit is set (Yes pathfrom 5B-5), as represented by block 5B-7, the method includes decidingthat the control field is a VHT control field.

FIG. 6A is a flowchart of an implementation of a method of communicatinga modulation coding scheme (MCS) indicator from an access terminal to anaccess point. As represented by block 6A-1, the method includesreceiving a frame from an access point or another access terminal. Asrepresented by block 6A-2, the method includes determining the frametype. As represented by block 6A-3, the method includes determining theMCS based at least in part on the frame type. As represented by block6A-4, the method includes transmitting an indicator of the determinedMCS.

FIG. 6B is a flowchart of an implementation of a method of communicatinga modulation coding scheme (MCS) indicator from an access terminal to anaccess point. As represented by block 6B-1, the method includesreceiving a frame. As represented by block 6B-1, the method includesdetermining whether the frame includes a request. If the frame includesa request (Yes path from 6B-2), as represented by block 6B-3, the methodincludes parsing the request for a sequence number. As represented byblock 6B-4, the method includes determining the MCS from the sequencenumber. As represented by block 6B-5, the method includes transmittingan indicator of the MCS to the access point.

Referring again to block 6B-2, if the frame includes a request (Yes pathfrom 6B-2), as represented by block 6B-6, the method includesdetermining the MCS from the most recent communication. As representedby block 6B-7, the method includes setting a reserved sequence number toindicate that the MCS report is unsolicited by the access point.

FIG. 7A is a flowchart of an implementation of a method of determiningan MCS type of a received frame. As represented by block 7-1, the methodincludes receiving a frame having a VHT control field. As represented byblock 7-2, the method includes parsing the VHT control field to identifya link adaptation control subfield.

As represented by block 7-3, the method includes determining if thevalue of the subfield is “00”. If the value of the subfield is “00”, asrepresented by block 7-4, the method includes deciding that the MCS typeis open loop (OL) MIMO.

As represented by block 7-5, the method includes determining if thevalue of the subfield is “01”. If the value of the subfield is “01”, asrepresented by block 7-6, the method includes deciding that the MCS typeis transmit beamforming (TxBF).

As represented by block 7-7, the method includes determining if thevalue of the subfield is “10”. If the value of the subfield is “10”, asrepresented by block 7-8, the method includes deciding that the MCS typeis multi-user (MU) MIMO.

As represented by block 7-9, the method includes determining if thevalue of the subfield is “11”. If the value of the subfield is not “11”,as represented by block 7-10, the method includes treating the subfieldas a reserved value. If the value of the subfield is not “11”, asrepresented by block 7-11, the method includes reporting an error.

In another implementation, the VHT control field includes a linkadaptation control subfield having an indicator that is at least fourbits. FIG. 7B illustrates an example of a link adaptation controlsubfield 750 where 4 bits of the link adaptation control subfield 750may be used as an indicator. The link adaptation control subfield 750includes a RSVD field 752 comprising 1 bit, followed by a MFSI_L field754 comprising 1 bit, followed by a MAI field 756 comprising 4 bits,followed by a MFSI_H field 758 comprising 3 bits, followed by aMFB/ASELC field 760 comprising 7 bits. The four bits of the linkadaptation control subfield 750 that make up the indicator may be thesecond, seventh, eighth and ninth bits of the link adaptation controlsubfield 750. As shown, the second bit is is the MFSI_L field 754, andthe seventh, eighth and ninth bits of the indicator is the MFSI_H field758. The value of the four bit indicator can be used to communicateinformation such as the MCS type. For example, in one implementation anindicator value of ‘1100’ can be used to indicate that the MCS typecomprises OL MIMO. Additionally, an indicator value of ‘1001’ can beused to indicate that the MCS type comprises open TxBF. Additionally, anindicator value of ‘1010’ can be used to indicate that the MCS typecomprises MU MIMO. Additionally, at least some of the values from ‘1011’to ‘1111’ can be utilized as reserved indicator sequences, one or moreof which can later be used to represent other information.

FIG. 8 is a flowchart of an implementation of a method of prompting anaccess point to request the measurement of at least one parametercharacterizing a wireless channel, which may be performed by an accessterminal. As represented by block 8-1, the method includes determiningan update condition. As represented by block 8-2, the method includestransmitting an update condition indicator to an access point. Asrepresented by block 8-3, the method includes receiving a request for ameasurement of at least one parameter characterizing a wireless channel.As represented by block 8-4, the method includes taking the measurement.As represented by block 8-5, the method includes transmitting a valueindicative of the measurement.

In certain aspects, a frame, such as the MAC frame 500, may be referredto as a “carried frame” and wrapped in another frame, which may bereferred to herein as a “wrapper frame.” Accordingly, the wrapper framecomprises the carried frame. The wrapper frame may be transmitted andreceived as part of a PPDU. The wrapper frame may also includeadditional information about the wrapper frame and the carried frame.The wrapper frame may comprise a type field, a subtype field, a controlfield, and the carried frame. Each of the type field, subtype field, andcontrol field may comprise one or more bits. The value of the bits mayindicate information about the wrapper frame and the control frame asdiscussed below.

The type field may indicate that the wrapper frame is a wrapper frame oranother type of frame. If the type field indicates the frame is awrapper frame, the subtype field may indicate that the wrapper frame isa wrapper for a control frame (the carried frame), or a wrapper for someother type of frame. If the type and subtype fields indicate the frameis a wrapper frame for a control frame, the control field may indicatewhether the carried frame uses an HT format or a VHT format (e.g., is aHT control frame or a VHT control frame). The control field may have areserved subfield, and the format of the carried frame may be based onthe value of the reserved subfield. The reserved subfield may comprise asingle bit. In some aspects, the reserved subfield may comprise aplurality of bits. For example, the reserved subfield may comprise atleast one of the 1^(st), 21^(st) or 22^(nd) bit in the control field,and any of the 26^(th)-30^(th) bits in the control field.

A receiver of the wrapper frame can process the carried frame based onthe determination it is a control frame and the format of the carriedframe. In particular, a receiver first determines the wrapper frame is awrapper frame carrying a control frame, then looks to the control fieldto determine the format of the control frame. The receiver then canprocess the carried control frame based on the determined format.

The carried control frame may have a similar format as MAC frame 500.For example, the carried control frame may comprise at least one of aduration field such as the duration field 504, an address field such asthe address 1 field 506, a carried frame control field such as the HTcontrol field 404, and an FCS field such as the FCS field 508.

FIG. 9A is a flowchart of an implementation of a method of determiningthe type of control field included in a frame wrapper having a carriedframe. As represented by block 9A-1, the method includes determining theframe wrapper type. As represented by block 9A-2, the method includesdetermining if the data unit type is VHT or HT. If the data unit type isHT (HT path from 9A-2), as represented by block 9A-3, a HT control fieldis present. If the data unit type is VHT (VHT path from 9A-2), asrepresented by block 9A-4, a VHT control field is present.

FIG. 9B is a flowchart of an implementation of another method ofdetermining the type of control field included in a frame wrapper havinga carried frame. As represented by block 9B-1, the method includesdetermining a frame wrapper type. As represented by block 9B-2, themethod includes parsing a frame control field to determine if a VHT orHT control field is present. If a control field is not present (No pathfrom 9B-3), the method includes stopping. If a control field is present(Yes path from 9B-3), the method includes parsing a reserved bit asrepresented by block 9B-5. If the reserved bit is not set (No path from9B-5), as represented by block 9B-6, the method includes deciding thatthe control field is a HT control field. On the other hand, is thereserved bit is set (Yes path from 9B-5), as represented by block 9B-7,the method includes deciding that the control field is a VHT controlfield.

In certain aspects a first wireless node, such as the AP 110, mayrequest channel state information (CSI) from a second wireless node,such as the UT 120. The UT 120 may respond to the request with the CSI.

FIG. 10 illustrates an exemplary CSI feedback protocol 1000. The AP 110may transmit to one or more user terminals 120 a Null Data PacketAnnouncement (NDPA) frame 1002 followed by a Null Data Packet (NDP)frame 1004 after a Short Inter-Frame Symbol (SIFS) period 1006. The NDPAframe 1002 may comprise Association Identifiers (AIDs) of the userterminals 120 that should transmit computed CSI feedback messages to theAP 110.

Those user terminals 120 that are not identified in the NDPA may ignorethe following NDP frame 1004. The NDP frame 1004 may comprise a soundingframe utilized by each of the identified user terminals 120 to computecorresponding CSI feedback. A first listed user terminal 120 within theNDPA frame 1002 may transmit CSI feedback 1008 subsequent to a SIFSperiod after the transmission of the NDP frame 1004, as illustrated inFIG. 10. Other identified user terminals 120 may be polled by utilizinga CSI poll message (or a sounding poll message) for each other userterminal 120, and may thereafter transmit CSI feedback to the AP 110.

FIG. 11 illustrates an exemplary NDPA frame 1002. In some aspects, theNDPA frame 1002 may be referred to as a CSI request message, which maybe of type control frame. The NDPA frame 1002 includes a frame controlfield 1102, a duration field 1104, an RA broadcast field 1106, a TAfield 1108, a CSI sequence (or sounding sequence) field 1112, an userterminal (STA) information field 1114, and a frame check sequence (FCS)field 1116.

In the illustrated aspect, the frame control field 1102 comprises 16bits, and the duration field 1104 comprises 16 bits and may include alength of the NDPA frame 1002. The RA broadcast field 1106 comprises 48bits, and may comprise a broadcast/multicast address for multiple STAs.The TA field 1108 comprises 48 bits, and may comprise an address oridentifier of a device transmitting the NDPA frame 1002.

The CSI sequence field 1112 comprises 8 bits. The CSI sequence field1112 may comprise a sequence number for the NDPA frame 1002 or otherdescriptor uniquely identifying the NDPA frame 1002.

The length of the STA information field 1114 may vary, and may includeinformation for each user terminal 120 from which CSI is requested. TheFCS field 1116 comprises 32 bits and may comprise data for determining acyclic redundancy check (CRC), as illustrated above.

A user terminal 120 identified in the NDPA frame 1002 and receiving theNDPA frame 1002 and NDP frame 1004 may respond with CSI information in aCSI feedback frame 1008.

In some aspects, the AP 110 may require or request that the CSI betransmitted using a particular modulation coding scheme (MCS) byindicating in a message to the user terminal 120 a particular MCS touse. The AP may choose the MCS based on feedback information it receivesfrom the user terminal 120, MCS Feedback (MFB). The MFB may include MCSestimates (estimates of which MCS is best used in the currentenvironment). In certain aspects, an AP 110 sends a request to the userterminal 120 for an MFB and the user terminal 120 responds with the MFB.The STA therefore calculates the MCS estimates based on characteristicsof the received request. Further, the AP 110 determines an MCS to beused based on the MFB and the characteristics of the request it sent tothe user terminal 120.

In some aspects, the user terminal 120 may be configured to transmit anunsolicited MFB to the AP 110, meaning the user terminal 120 sends anMFB without receiving a request for an MFB from the AP 110. The AP 110is not expecting the MFB, and therefore does not know whichcommunication from the AP 110 the user terminal 120 based the MFB on.The AP 110 needs to know which communication the user terminal 120 basedthe MFB on in order to properly select an MCS for communication.

Accordingly, when the AP 110 receives the unsolicited MFB, the AP 110first determines it is an unsolicited MFB. The AP 110 may make thisdetermination based on an indicator (e.g., a field (e.g., an MFSI (MCSFeedback (MFB) Sequence Identifier) field) in the MFB that indicates itis an unsolicited MFB. The AP 110 then determines which communication(e.g., one of a plurality of communications the AP 110 transmitted tothe user terminal 120) the MFB is based on. In order to help the AP 110make this determination, the MFB may also include a group ID (GID)field, a beamforming field, and/or may be transmitted using a particularMCS. The AP 110 may then identify which communication the AP 110 mostrecently sent to the user terminal 120 has a GID, a beamforming value,and/or used a MCS that matches that of the MFB. The communication mostrecently sent in time with matching characteristics is identified as thecommunication for which the MFB was sent. The AP 110, using the MFB andthe identified communication, may then determine an MCS for the userterminal 120 to use. The AP 110 may then transmit an indication to theuser terminal 120 of the MCS to be used and/or transmit data itselfusing the MCS.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrate circuit (ASIC), or processor. Generally,where there are operations, module, or steps illustrated in Figures,those operations may have corresponding counterpart means-plus-functioncomponents. For example, a user terminal may comprise means forreceiving a frame having a control field, means for determining whetherthe control field comprises a first type or a second type based at leastin part on the control field, and means for processing the control fieldbased on the determined type.

FIG. 12 illustrates a block diagram of an example user terminal 1200 inaccordance with certain aspects of the present disclosure. User terminal1200 comprises a receiving module 1205 which may be configured toperform the functions of the means for receiving discussed above. Insome aspects, the receiving module may correspond to one or more of thereceivers 254 of FIG. 2. User terminal 1200 further comprises adetermining module 1210 which may be configured to perform the functionsof the means for determining discussed above. In some aspects, thedetermining module may correspond to the controller 280 of FIG. 2. Userterminal 1200 further comprises a processing module 1215 which may beconfigured to perform the functions of the means for processingdiscussed above. In some aspects, the processing module may correspondto the controller 280 of FIG. 2.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logic device(PLD), discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

In one or more aspects, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media may be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Thus, in some aspects computer readable medium may comprisenon-transitory computer readable medium (e.g., tangible media). Inaddition, in some aspects computer readable medium may comprisetransitory computer readable medium (e.g., a signal). Combinations ofthe above should also be included within the scope of computer-readablemedia.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

The functions described may be implemented in hardware, software,firmware or any combination thereof. If implemented in software, thefunctions may be stored as one or more instructions on acomputer-readable medium. A storage media may be any available mediathat can be accessed by a computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For certain aspects, the computer program product may includepackaging material.

Software or instructions may also be transmitted over a transmissionmedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition oftransmission medium.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

While the foregoing is directed to aspects of the present disclosure,other and further aspects of the disclosure may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method of wireless communication, comprising: receiving a first frame having a control field and a frame control field, wherein the control field and the frame control field are separate fields; determining whether the control field comprises a first type or a second type based at least in part on an indication in the control field, wherein the first type is very high throughput (VHT) and the second type is high throughput (HT); and processing the control field based on the determined type, wherein the first frame is a wrapper frame that comprises the control field and a second frame, and further comprising processing the second frame based on the determined type, wherein the wrapper frame comprises one or more bits in a location of the control field corresponding to a reserved subfield of the control field.
 2. The method of claim 1, wherein the indication comprises a bit within the control field, the method further comprising evaluating the bit within the control field, and determining that the second frame is a VHT control frame based on the bit.
 3. The method of claim 2, wherein the control field further comprises at least one of a duration field, an address field, a carried frame control, or a FCS field.
 4. The method of claim 2, wherein the control field comprises a VHT control field comprising at least one of a link adaptation control subfield, a reserved subfield, an AC constraint subfield, or a RDG subfield.
 5. The method of claim 4, wherein the link adaptation control subfield comprises 16 bits, wherein the reserved subfield comprises 14 bits, wherein the AC constraint subfield comprises 1 bit, and wherein the RDG subfield comprises 1 bit.
 6. The method of claim 1, wherein the indication comprises a bit within the control field, the method further comprising evaluating the bit within the control field, and determining that the second frame is a HT control frame based on the bit.
 7. The method of claim 1, wherein the location comprises at least one of the 1^(st), 21st or 22nd bit in the control field and any of the 26th-30th bits in the control field.
 8. The method of claim 1, wherein the wrapper frame is received in a physical layer protocol data unit (PPDU).
 9. The method of claim 1, further comprising determining that the first frame comprises a VHT wrapper based on the frame control field.
 10. The method of claim 1, wherein the first frame comprises a type field that indicates the first frame is a wrapper frame.
 11. The method of claim 1, wherein the first frame comprises a subtype field that indicates the first frame is a wrapper for a control frame.
 12. An apparatus for wireless communication, comprising: a circuit configured to receive a first frame having a control field and a frame control field, wherein the control field and the frame control field are separate fields; and a processor configured to: determine whether the control field comprises a first type or a second type based at least in part on an indication in the control field, wherein the first type is very high throughput (VHT) and the second type is high throughput (HT); and process the control field based on the determined type, wherein the first frame is a wrapper frame that comprises the control field and a second frame, and wherein the processor is further configured to process the second frame based on the determined type, wherein the wrapper frame comprises one or more bits in a location of the control field corresponding to a reserved subfield of the control field.
 13. The apparatus of claim 12, wherein the location comprises at least one of the 1^(st), 21st or 22nd bit in the control field and any of the 26th-30th bits in the control field.
 14. The apparatus of claim 12, wherein the wrapper frame is received in a physical layer protocol data unit (PPDU).
 15. The apparatus of claim 12, further comprising determining that the first frame comprises a VHT wrapper based on the frame control field.
 16. The apparatus of claim 12, wherein the first frame comprises a type field that indicates the first frame is a wrapper frame.
 17. The apparatus of claim 12, wherein the first frame comprises a subtype field that indicates the first frame is a wrapper for a control frame.
 18. An apparatus for wireless communication, comprising: a circuit configured to receive a first frame having a control field and a frame control field, wherein the control field and the frame control field are separate fields; and a processor configured to: determine whether the control field comprises a first type or a second type based at least in part on an indication in the control field, wherein the first type is very high throughput (VHT) and the second type is high throughput (HT); and process the control field based on the determined type, wherein the first frame is a wrapper frame that comprises the control field and a second frame, and wherein the processor is further configured to process the second frame based on the determined type, wherein the indication comprises a bit within the control field, and wherein the processor is further configured to: evaluate the bit within the control field; and determine that the second frame is a VHT control frame based on the evaluation.
 19. The apparatus of claim 18, wherein the control field further comprises at least one of a duration field, an address field, a carried frame control, or a FCS field.
 20. The apparatus of claim 18, wherein the control field comprises a VHT control field comprising at least one of a link adaptation control subfield, a reserved subfield, an AC constraint subfield, or a RDG subfield.
 21. The apparatus of claim 20, wherein the link adaptation control subfield comprises 16 bits, wherein the reserved subfield comprises 14 bits, wherein the AC constraint subfield comprises 1 bit, and wherein the RDG subfield comprises 1 bit.
 22. An apparatus for wireless communication, comprising: a circuit configured to receive a first frame having a control field and a frame control field, wherein the control field and the frame control field are separate fields; and a processor configured to: determine whether the control field comprises a first type or a second type based at least in part on an indication in the control field, wherein the first type is very high throughput (VHT) and the second type is high throughput (HT); and process the control field based on the determined type, wherein the first frame is a wrapper frame that comprises the control field and a second frame, and wherein the processor is further configured to process the second frame based on the determined type, wherein the indication comprises a bit within the control field, and wherein the processor is further configured to: evaluate the bit within the control field; and determine that the second frame is a HT control frame based on the evaluation.
 23. A user terminal for wireless communication, comprising: an antenna; a receiver configured to receive, via the antenna, a frame having a control field and a frame control field, wherein the control field and the frame control field are separate fields; and a processor configured to: determine whether the control field comprises a first type or a second type based at least in part on an indication in the control field, wherein the first type is very high throughput (VHT) and the second type is high throughput (HT); and process the control field based on the determined type, wherein the frame is a wrapper frame that comprises the control field and another frame, and further comprising means for processing the other frame based on the determined type, wherein the wrapper frame comprises one or more bits in a location of the control field corresponding to a reserved subfield of the control field. 